But my experience with FreeBSD's docs are even better - and most of that experience is quite old at this point. I can't imagine how much better the situation has gotten since FreeBSD only seems to mature and not degrade (based on comments like yours which are very common).
I also seriously dislike the BSD's tendency towards making --help useless, forcing you to bring up the man page. This is just for practical reasons. It's easier to hit up arrow, dash dash help pipe less than up arrow, ctrl+a, man, alt+f, ctrl+k to kill the arguments you've already written :)
/me adds a new project to the backlog...
Man pages in OpenBSD for instance are a "must". In the GNU world, often man pages are really badly maintained pointing to GNU info. Also, the so called "Linux Howtos" were a disaster full of obsolete points.
Just compare the OpenBSDxy.html upgrading page (where m and n are release numbers) for OpenBSD releases (and the FAQ) to the Arch Wiki.
OpenBSD also strikes a very good balance between "informative" and "terse" that should be held up as a model for others. Unfamiliar things may need a few readings to get everything, but it's all there without being a toilet-clogger.